1. Field of the Invention
This invention relates generally to surgical implants for repairing continuity defects in bones, such as the mandible.
2. Prior Art
Discontinuities in bones, such as the mandible or jaw bone, may comprise of a fracture caused by an accident, or a missing section caused by the surgical removal of a diseased portion. The defects are commonly repaired by attaching a bar of titanium, stainless steel, or other metal alloy, across the fracture or gap. A typical bar includes a series of screw holes and intermediary segments. The bar is attached to the mandible with screws positioned through the holes. However, it must be cut to size and accurately bent to conform to the contour of an individual mandible before installation. Due to the stiffness of the bar and the accuracy required, cutting and bending the bar may take two hours or longer. If the bending is not completely accurate, the mandible is stressed when the bar is tightened thereon, and also deformed to prevent proper dental occlusion. Further, the narrow intermediary segments between the screw holes create stress points, which are exacerbated by bending, where failure sometimes occur. If broken, the entire bar must be surgically removed and replaced, causing further suffering to the patient.
U.S. Pat. No. 4,225,668 to Bartoli shows a dental support bar for mounting dentures. It is comprised of segments connected by pins. Threaded sleeves are screwed onto the pins. Plates attached to the lower end of the pins are embedded in the gum. The segments are disclosed as requiring bending to follow the gum line. The dental support bar cannot be used for repairing discontinuities in a mandible, because the pins are merely attached to the gum, and the pivots between the bar segments are not tightly connected enough to remain rigid, i.e., the bar relies on the mandible for stability. It can only be used on a part of the jaw which is normal, i.e., without a reconstruction bar.
U.S. Pat. No. 5,219,286 to Hader shows another dental support bar for mounting dentures. It is comprised of segments connected by ball-and-socket joints attached to the jaw by posts. The segments arc extendable to allow for unequal spacing between the joints. The support bar thus relies on the jaw for stability, so that it cannot be used for reconstructing a broken jaw. It must also be used in combination with a mandible reconstruction bar when there is a discontinuity in the mandible. It can also only be used on a part of the jaw which is normal.